Is Neural Language Model Perplexity Related to Readability?

This paper explores the relationship between Neural Language Model (NLM) perplexity and sentence readability. Start-ing from the evidence that NLMs implicitly acquire sophisticated linguistic knowledge from a huge amount of training data, our goal is to investigate whether perplexity is affected by linguistic features used to automatically assess sentence readability and if there is a correlation between the two metrics. Our findings suggest that this correlation is actually quite weak and the two metrics are affected by different linguistic phenomena. 1